Process for cold forming tube ends

Abstract

A process for cold forming the ends of metal tubes to reinforce same includes a die cavity into which the tube is placed. The die cavity includes a section with a recess having a greater diameter than the tube. The tube is placed such that a portion is left outside of the cavity and a mandrel is inserted into the tube. The mandrel includes a section that is adapted to bear against the portion of the tube outside of the cavity and to deform same. The deformation process results in the tube being folded upon itself within the recess in the cavity thereby forming a reinforcing flange at the end of the tube. The process is conducted without heating the tube.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
         1 . A process for reinforcing an end of a metal tube having inner and outer surfaces and first and second ends, the process comprising the steps of: 
 a) providing a die having first and second ends and defining a cavity conforming to the outer surface of said tube, the cavity having a recess at said first end that is wider than the tube;    b) placing the tube in said die cavity such that said tube first end extends out of said die cavity beyond said die first end;    c) providing a means for preventing movement of the tube longitudinally with respect to said die cavity;    d) providing a mandrel having a first portion adapted to fit within said tube through said tube first end, the mandrel also having a second portion with a tube deforming surface adapted to impinge upon said tube first end;    e) inserting said mandrel first portion into the first end of said tube until the tube deforming surface contacts the first end of the tube;    f) advancing the mandrel under pressure thereby causing deformation of the first end of the tube and folding of same into the recess of said die cavity.    
     
     
         2 . The process of  claim 1  wherein said mandrel first portion conforms to the inner surface of the tube.  
     
     
         3 . The process of  claim 1  wherein said means for preventing movement of the tube comprises a barrier.  
     
     
         4 . The process of  claim 1  wherein said tube has a circular or rectangular cross section.  
     
     
         5 . A tube deformed according to the process of  claim 1 .  
     
     
         6 . The process of  claim 1  wherein the tube comprises a hitch bar receiver tube.  
     
     
         7 . A tube having a first end wherein said first end includes a radially extending reinforced portion comprising a section of the tube folded upon itself.  
     
     
         8 . The tube of  claim 7  wherein the tube comprises a hitch bar receiver tube.